They respond very well to subzero but the QPI is limiting at 4 Ghz so it doesn't matter if it's -30 or -190.
Water is great for 24/7 run with a decent overclock for i7.
I can work on 4.2Ghz with HT=ON 24/7 and my temps top at about 70c degrees for the highest core, the colder ones are about 68c degrees.
The GTZ is an awesome block, I would definitely buy it for the i7.
